On the convergence of the normalized power sequence of spectral operators on Hilbert space

Fuente: arXiv
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Autores principales: Nayak, Soumyashant, Shekhawat, Renu
Formato: Preprint
Publicado: 2024
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author Nayak, Soumyashant
Shekhawat, Renu
author_facet Nayak, Soumyashant
Shekhawat, Renu
contents Let $\mathscr{H}$ be a complex Hilbert space, and let $\mathscr{B}(\mathscr{H})$ denote the set of all bounded operators on $\mathscr{H}$ . For an operator $T \in \mathscr{B}(\mathscr{H})$, let $|T| := (T^*T)^{\frac{1}{2}}$. For $A$ in $\mathscr{B}(\mathscr{H})$, we refer to the sequence, $\{ |A^n|^{\frac{1}{n}} \}_{n \in \mathbb{N} }$, as the $\textit{normalized power sequence}$ of $A$. As our main result, we prove that the normalized power sequence of a spectral operator in $\mathscr{B}(\mathscr{H})$ converges in norm, and provide an explicit description of the limit in terms of its idempotent-valued spectral resolution. Our approach substantially generalizes the corresponding result by the first-named author in the case of matrices in $M_m(\mathbb{C})$, and supplements the Haagerup-Schultz theorem on SOT-convergence of the normalized power sequence of an operator in a $II_1$ factor.
format Preprint
id arxiv_https___arxiv_org_abs_2410_16318
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the convergence of the normalized power sequence of spectral operators on Hilbert space
Nayak, Soumyashant
Shekhawat, Renu
Functional Analysis
Operator Algebras
47B40, 47A10, 15A18
Let $\mathscr{H}$ be a complex Hilbert space, and let $\mathscr{B}(\mathscr{H})$ denote the set of all bounded operators on $\mathscr{H}$ . For an operator $T \in \mathscr{B}(\mathscr{H})$, let $|T| := (T^*T)^{\frac{1}{2}}$. For $A$ in $\mathscr{B}(\mathscr{H})$, we refer to the sequence, $\{ |A^n|^{\frac{1}{n}} \}_{n \in \mathbb{N} }$, as the $\textit{normalized power sequence}$ of $A$. As our main result, we prove that the normalized power sequence of a spectral operator in $\mathscr{B}(\mathscr{H})$ converges in norm, and provide an explicit description of the limit in terms of its idempotent-valued spectral resolution. Our approach substantially generalizes the corresponding result by the first-named author in the case of matrices in $M_m(\mathbb{C})$, and supplements the Haagerup-Schultz theorem on SOT-convergence of the normalized power sequence of an operator in a $II_1$ factor.
title On the convergence of the normalized power sequence of spectral operators on Hilbert space
topic Functional Analysis
Operator Algebras
47B40, 47A10, 15A18
url https://arxiv.org/abs/2410.16318